Horn radiator adapted to produce circularly polarized waves



H. J. RIBLET ET AL 2,635,190 HORN RADIATOR ADAPTED TO PRODUCE CIRCULARLY POLARIZEDWAVES Filed May 24, 1946 April 14, 1953 INV HENRY J. DORA F. S

ENTORS RIBLET HERMAN ATTORNEY 3 m B B F T y 1, 9 9 g a l n M 9 l w l N a w w m m w m Patented Apr. 14, i953 :i'

HORN RADIATOR ADAPTED TO PRODUCE CIRCULARLY POLARIZED WAVES Henry J. Riblet, Belmont, Mass., and Dora F. Sherman, Ithaca, N. Y., assignors, by mesne assignments, to United States of America as represented by the Secretary of 'War Application May 24, 1946, Serial No. 672,021

This invention relates to devices for radiating waves of electromagnetic energy such as used in high frequency communication systems including radio object-locating systems. More particularly the invention is directed to a device for adapting the principles of a flared horn type radiating element directly to the termination of a coaxial conductor transmission line or the like and for producing circularly polarized radiant energy.

A radiating element of the horn type has wide application and can be used to match a waveguide transmission line to free space and thus may be used to radiate waves of electromagnetic energy directly to free space. Another application is in feeding energy to and illuminating a reflector adapted to direct energy into free space in any desired radiation pattern. Heretofore, a horn type radiating element has required a hollow pipe waveguide for feeding energy thereto. In the cases where the energy is transmitted from its source'by a coaxial line, it has been necessary to have a coupling device from the coaxial line to a hollow pipe waveguide for feeding the horn. The'present invention eliminates the need for a coupling device by terminating a coaxial conductor type transmission line in a flared horn type section.

Accordingly, it is one of the objects of the present invention to provide a flared termination to a coaxial conductor line whereby energy may be radiated directly therefrom.

It is another object of the invention to provide a horn type termination to a coaxial transmission line and in which the inner conductor is disposed in such a manner that it is eifectiv'e as a dipole section, the orientation of the dipole section determining the plane of polarization of the radiant energy.

It is still another object of the invention to provide a coaxial horn antenna with means whereby circular polarization of the radiant energy is afforded (polarization being defined in the sense used in the radio art rather than in theoflicial sense and referring here to the direction of the electric vector rather than that of the magnetic vector).

For a better understanding of the invention together with other and further objects thereof, reference is had to the following description of the invention taken in connection with the accompanying drawing, in which:

Fig. 1 is a perspective view of a coaxial horn antenna according to the present invention;

Fig. 2 is a perspective view of a weatherizing structure adapted tqfit th horn of Fig. 1; and

4: Claims. (01. 25033.63)

polarized energy to a circularly polarized one.

It is noted that the member I8 is shorter and U of a smaller cross-sectional dimension than the main radiating element comprising the bent end. portion I6 Because oflthese differences, the. current which flows in member.v I tiv is. essentially;

Figs. 3 and 4 are sectional views taken along the lines of 33 and 4-4 of Fig. 2, respectively.

Referring to Figs. 1, 3 and 4, there is shown a flared horn structure I0 having an outer flared conductor II and an inner conductor I2 adapted to be connected at the throat portion I3 to a coaxial conductor transmission line. Any suitable means may be provided for making the connection, for example, the outer surface of the throat portion I3 may be threaded to provide threaded engagement to the outer conductor of the coaxial transmission line or a suitable coupling member I3 may be provided. The end of the inner conductor I2 of the horn at the throat I3 may have a sliding fit with or any other suitable coupling to the inner conductor of the coaxial transmission line. From the throat portion I3, the outer conductor II is flared out in a relatively smooth manner to provide a circular mouth termination I4, preferably the flared portion I! is bent or curved smoothly so that the plane of the aperture of the mouth I4 is substantially parallel to the axis of the throat portion I3.

til close to the aperture plane and then bent substantially at a right angle as at I5 so that the bent end portion I6 is substantially parallel to. the plane of the mouth I4. The free end I! of inner conductor I2 may, if desired, actually touch the periphery of the circular mouth I4 7 although as shownit is preferred that there be a slight spacing between the peripheral mouth portion and the end I! of the inner conductor I 2. Adjacent the right angle bend I5 of inner con-.

ductor I2 is a relativelyshort rod, bar or strip effect a dipole radiating element, which is reso-.

nant at the operating frequency, the orientation of the bent portion I6 determining the plane of polarization of the radiant energy. Thus when the bent portion I6 is disposed in a vertical or horizontal manner, vertical or horizontal polarie zation of the radiant energy respectively results. The addition to the member I 8 converts the plane The inner conductor I2 is bent to follow the approximate axis of the flared portion I I un- 3 90 in time phase with the current which flows in member l8. Since the members l6 and 18 are also oriented at 90 with each other in space phase the necessary relationships exist to produce circularly polarized energy.

In order to provide additional support to the inner conductor member H and the end portion 16, a supporting member l9 may be inserted in the flared portion of the hornin av generally diametrical manner. This supporting member: t9 may be a suitably shaped strip of dielectric material and is provided with recesses" or slots 20 and 2! for accommodating inner conductor 1'2 with its. bent end portion l6 and member [8" respectively; To prevent the effect of changes in Weather and pressure, the horn may be closed and sealed by means of the weatherizing member 22 as shown in Fig. 2 which is shaped to fit Within the mouth I; of the flared horn portion and is provided with recesses; slots org-reeves 23*- and 24 for receiving the supporting member l9 and to provide clear ance for the member 18 respectively. The slot 24' should be carefully dimensioned as the size thereof may affect the radiation from member 18.

It has" been found that an antenna comprising the flared 'hornterminationto acoaxi'al transmission linesuch asdesoribed' hereinbefore has produced extremely satisfactory results in affording circular polarization over a broad band of frequencies.

While there has been. described what isat present considered the preferred embodiment of the invention, it'will be obvious to those skilled in the art that variouschanges and modifications may be made therein without departing from the invention.

What is claimed is? I. A device for radiating circularly polarized waves of electromagnetic energy adapted to be connected directlyto a coaxial conductor transmission line com-prising an outer conductor in the shape of a smoothly flaring horn having a throat portion adapted tobe'oonne'ctedto the outer conductor of said coaxial line and a portion flaring smoothly and evenly outwardly on all sides from said throat portion with its end defining a substantially circular aperture, an inner conductor located substantially centrally within said outer conductor, one end of said inner conductor being adapted to be connectedto the central. conductor U ofsaidcoaX-ial line, the opposite end portion of said inner conductor being bent toward the end of said flaring portion defining said aperture, said bent end-portion being substantially in the plane or said circular aperture, and a substantially straight member-connected-tosaid bent end portion adjacent the point of bending thereof, said member extending outwardly substantially at aright angle from said bent end portion substantially in the plane-of said circular-aperture, whereby saidbent' end portion and said member are oriented at 90' with each: other: in space phase, said member'being of smaller cross-section and length than said. bent, end portion whereby the energy currents in. said: member andv said. end.

portion are'substanti'all'y in 90 time: phase when.

said bent end: is resonant at the; operating frequency; said device thereby being adapted to radiate circularly polarized energy at said operating. frequency;

2; A. horn-shaped radiating element comprising. an outer conductor flaring. outwardly to form horn with an outer-circular aperture, an inner conductor located substantially centrally of said length, the end of said inner conductor near the aperture of said horn being bent toward the end of said horn to eifectively afford a dipole radiating element, said bent end portion being substantially inthe plane of said aperture, and a substantially straight member extending from the bent end portion adjacent the bend therein and at substantially 90 to said bent end portion substantially in the plane of said aperture, said member being of smaller cross-section and length than said bent end portion whereby said bent end portion and said member cooperate to radiate circularl'y polarized energy from said element when properly energized.

3. A device for radiating circularly polarized waves: comprising first radiating means in the form of afirst straight conductor of a given crosssection and length so as to be resonant at a given frequency, means connected to one end of said first conductor for feeding said first conductor with ultra-high frequency electromagnetic energy of said given frequency, and second radiating means in the form of a-second straight conductor connected at one end directly to said one end of said first conductor and oriented perpendicular to said first conductor, said second conductor having a sufficiently smaller cross-section and length than said first conductor so as to be non-resonant at said given frequency, whereby said second cond'uctoris energized in 90 time phase relationship with respect to the energization of said first conductor at said given frequency.

4. A device for radiating circularly polarized energy comprising a first radiator having a given cross-sectional area and resonant at a given frequency, a second radiator having across-sectional area. substantially smaller than that of said first radiator and non-resonant at saidgiven frequency, means-for applying. to the inputs of both radiators in phase exciting voltages having said.-

given frequency, and said first radiator being oriented at an angle of substantiaily so with respect to said. second radiator.

HENRY J .RI'BLET. DORA SHERMAN References Cited in the file. of this patent UNITED STATES PATENTS Number Name Datel,915,784 Hammond June27, 1933 1,933,911 Taylor Nov. 7, 1933' 1,974,545 Salts Sept. 25,v 1934 2,110,159 Landon et. a1. Mar. 8-, 1938 2,181,870 Carter Dec. 5, 1939 2,281,274 Dallenbach .Apr. 28, 1942: 2,307,011 Barrow Jan. 5,1943 2,307,012 Barrow Jan. 5, 1943 2,312,799 Carter n i i Mar 2, 1943 2,364,084 Martin Dec. 5,.1944 2,403,500 Carlson July 9, 1946' $409,183 Beck Oct. 15, 1946 2,412,320 Carter Dec. 10, 1946' 2,413,187 McCurdy et al Dec.24=,.1946 2,425,716 Barrow Aug. 19. 1947 2,532,428 Smith Dec. 5,1950 FOREIGN PATENTS- Number Country Date 548,193 Great Britain Sept. 30', 1942 OTHER REFERENCES traeHigir-Frequency Techniques, by Brainerd 'et alz,v pages 415-422 (11th print), published by outer: c'onductor: for the major portion of vaniNostrandicog, 

